What are some of important discussions Imam included in his famous work “Forty Hadith”?

Believers are invited to divine banquet in Ramadan, Imam Khomeini explained

Imam Khomeini advised believers and faithful people that they should participate properly in the feast of Allah.

Imam Khomeini stressed spiritual transformation during Laylat al-Qadr

Imam Khomeini, the late founder of the Islamic Republic, recommended faithful and believers to undertake serious efforts for a spiritual transformation during Laylat al-Qadr.

Imam Khomeini: I request the non-commissioned officers, the officers, and the troops to maintain ...

Sahifeh-ye-Imam, Vol 7, Page 85

Imam Khomeini described Ramadan as divine feast

Imam through his messages and theological works highlighted the philosophy of divine feast during the blessed month.

Supplications by Imam Zain-ul-Abedin (PBUH) contains deep Quranic concepts, treasures of mysticism

Imam Khomeini, the late founder of the Islamic Republic maintained that divine-oriented supplications by Ali ibn Husayn Zain-ul-Abedin (PBUH) contain treasure of mysticism, deep Quranic cconcepts and several discipline of knowledge.

Imam Khomeini advised believers to perform worship with tranquility of mind

Imam Khomeini through his theological works recommended that the sālik should perform his worship with quietude of the heart and a tranquility of the mind.

Impeccability [ismat] is perfect faith, Imam Khomeini defined

The meaning of the impeccability of the prophets and the Friends of God [awliya] is not that, for instance, Gabriel took them by the hand.